Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of United Online (NASDAQ:UNTD) have plunged today by as much as 12% after the company reported first-quarter earnings.

So what: Revenue in the first quarter added up to $247.4 million, topping the Street's forecast of $243.4 million. Adjusted earnings per share were $0.16, right on target with analysts' best guesses. The company is proceeding along its plan to spin off the FTD business as an independent, publicly traded company.

Now what: CEO Mark Goldston said he would be leaving the company following the spin-off after 14 years as CEO. That revelation has created substantial uncertainty for United Online and FTD, which could be rattling investors. The United Online board will be searching for a new CEO once the spin-off is complete, and FTD President Rob Apatoff will become FTD's CEO.

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Fool contributor Evan Niu, CFA, has no position in any stocks mentioned. The Motley Fool owns shares of United Online. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.